AB0989 ARE OSTEOPOROSIS AND FRACTURES NEGLECTED ISSUES IN AXIAL SPONDYLOARTHRITIS? DATA FROM A CROSS-SECTIONAL MONOCENTRIC STUDY
Authors: C. Crotti, F. Orsini, R. Di Taranto, M. Ferrito, A. Amati, M. Biggioggero, M. Varenna, E. G. Favalli, R. Caporali
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Prevalence of osteoporosis (OP) and fractures (Fx) in spondyloarthritis (SpA) is frequently overlooked<sup>[1]</sup>. Axial (ax-) involvement, particularly in ankylosing spondylitis (AS), is associated with seeming increased lumbar spine bone mineral density (BMD) while vertebral fractures are present in up to 43% of patients with AS. Bone densitometry is considered the gold standard for osteoporosis diagnosis and fracture risk assessment. <h3>Objectives</h3> To investigate predictors of OP and prevalence of Fx in a population of ax-SpA patients. <h3>Methods</h3> Data were cross-sectionally extracted from a monocentric registry including SpA patients with axial involvement [AS, ax- Psoriatic Arthritis (ax-PsA), non-radiographic ax-SpA (nr-axSPA), IBD associated-SpA] at their last evaluation in a tertiary rheumatology center between August and December 2022. Comparisons were performed by T test and chi-square test; logistic regression was used to analyze the predictors of OP screening assessed by dual-energy x-ray absorptiometry (DXA) and other collected variables. <h3>Results</h3> The overall population included 385 patients (35.6% female; mean age±SD 48.5±12.7 yrs; 42.9% AS, 33% nr-axSpA, 20.5% ax-PsA, 3.6% IBD-SpA; 43.9% HLAB27 positive; 42.3% postmenopausal females; 7.8% patients with previous diagnosis of OP). Almost 10% of the entire population experienced Fx (n=38): 16 vertebral Fx, 2 femoral Fx, and 24 non-vertebral/non femoral Fx. The presence of previous fragility Fx was significantly associated with menopause (39% vs 12.4%, p&lt;0.001), older age (56.6±10.11 vs 47.6±12.65, p&lt;0.001), elevated ESR (median 13 mm/h (IQR 7-24) vs 9 (5-19), p=0.04) and higher ASDAS-CRP (median 1.28 (1-2.6) vs 1.05 (0.6-1.7), p=0.03), and previous OP diagnosis (50% vs 3.1%, p&lt;0.001). DXA was performed only in 11.7% of the population. DXA was mainly performed in females (64.5% vs 31.8%, p&lt;0.001), post-menopausal women (57.8% vs 9.4%, p&lt; 0.001), older patients (58.6±12.5 vs 47.2±8.9, p&lt;0.001), patients with previous diagnosis of disthyroidism (11.1% vs 4.7%, p=0.08), OP (53.4% vs 1.8%, p&lt;0.001), patients with previous Fx (46.7% vs 5%, p&lt;0.001), both vertebral Fx (26.7% vs 1.2%, p&lt;0.001) and non-vertebral/non femoral Fx (24.5% vs 3.9%, p&lt;0.001). DXA was significantly more frequently performed in patients supplemented with vitamin D (86.7% vs 29.4%, p&lt;0.001), calcium (53.4% vs 4.1%, p&lt;0.001), and receiving bisphosphonate therapy (26.7% vs 1.8%, p&lt;0.001) or on bone loss inducing drugs (44.4% vs 21.3, p=0.001). DXA was significantly less frequently evaluated in current smokers (1.5% vs 24.7%, p=0.04) and ax-PsA subtype (8.9% vs 22%, p=0.04). Factors associated with OP screening by DXA were menopause [OR 17.8, 95% CI 2.3-135, p=0.005], and bone loss inducing drugs (OR 3.2, 95% CI 1.12-9.16, p=0.030). Predictor of Fx was the presence of elevated disease burden expressed as ASDASCRP (OR 1.9, 95% CI 1.2-3.2, p=0.012). <h3>Conclusion</h3> Our data confirm that OP is an underestimated comorbidity in axSpA patients, particularly males or younger patients. Fragility Fx is related with disease burden, confirming that inflammation mostly triggers bone loss. Not all risk factors for OP are correctly addressed, such as active smoke. We should aim to better evaluate OP as a SpA comorbidity to early detect patients at high risk of fragility Fx to treat them properly. <h3>References</h3> [1]Magrey MN et al, Curr Rheumatol Rep. 2017;19:17. [2]Walsh JA et al, Clin Rheumatol. 2018;37:1869–1878. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.